No, they are people. They are said to be saints.
Probably 12 representing the 12 tribes of Israel (Old testament) and 12 apostles (New Testament).
There are angels too around the throne, but they are clearly described.

Four-and-twenty seats around the throne, were filled with four-and-twenty elders, representing, probably, the whole church of God. Their sitting denotes honour, rest, and satisfaction; their sitting about the throne signifies nearness to God, the sight and enjoyment they have of him. They were clothed in white raiment; the imputed righteousness of the saints and their holiness: they had on their heads crowns of gold, signifying the glory they have with him.